Land Types (land + type)

Distribution by Scientific Domains

Selected Abstracts

Effects of spatial variations in source areas upon dust concentration profiles during three wind erosion events in Australia

H. J. Butler
Abstract Dust storms are a major contributor to soil erosion in inland Australia, and the Simpson Desert,Channel Country region is one of the most active wind erosion regions. While information is available on wind erosion rates at the land-type level, little is known about the influence that spatial variations in the erodibility within a land type have on the resulting dust concentration profile. A Gaussian plume model, DSIS, is presented along with tower-based dust data, to describe the influence of different spatial combinations of dust source areas, during three dust events on the Diamantina River floodplain in Western Queensland, Australia. Copyright 2001 John Wiley & Sons, Ltd. [source]

Spatial distribution and its seasonality of satellite-derived vegetation index (NDVI) and climate in Siberia

Rikie Suzuki
Abstract The Normalized Difference Vegetation Index (NDVI) distribution and its seasonal cycle were investigated in relation to temperature and precipitation over Siberia and its surrounding regions. The analyses used 5-year (1987,1991) monthly means. The monthly mean NDVI was calculated from the third-generation monthly Global Vegetation Index (GVI) product; monthly temperature and precipitation at 611 stations were calculated from Global Daily Summary (GDS) data. The 611 stations were classified by cluster analysis into 10 classes based on the NDVI seasonal cycle (March,October). The geographical distribution characteristics of the NDVI cycle were described using temperature, precipitation and Olson's land-cover type. In northern regions, where tundra vegetation prevails and temperatures and precipitation are low, the amplitude of the NDVI seasonal cycle is small. In southern regions, where temperatures are high and there is little precipitation, the seasonal amplitude of the NDVI is small because of the arid land type. Forested regions were split into six classes, each characterized by large amplitudes in the NDVI seasonal cycle. The phenological characteristics of the forest classes were noted. For example, a forest-class localized near Lake Baikal shows higher NDVI values, even with the presence of snow cover in March, compared with other regions. This high NDVI value suggests that the exposed green canopy of the coniferous forest can be observed even when snow is present. In addition, the NDVI peaks at stations near 60N, where the maximum monthly temperature is around 18C. This result suggests that the optimum temperature-precipitation environment coincides to the area in Siberia where the maximum monthly temperature is 18C. Copyright 2001 Royal Meteorological Society [source]

Do arthropod assemblages display globally consistent responses to intensified agricultural land use and management?

GLOBAL ECOLOGY, Issue 5 2008
S. J. Attwood
ABSTRACT Aim, To determine whether arthropod richness and abundance for combined taxa, feeding guilds and broad taxonomic groups respond in a globally consistent manner to a range of agricultural land-use and management intensification scenarios. Location, Mixed land-use agricultural landscapes, globally. Methods, We performed a series of meta-analyses using arthropod richness and abundance data derived from the published literature. Richness and abundance were compared among land uses that commonly occur in agricultural landscapes and that represent a gradient of increasing intensification. These included land-use comparisons, such as wooded native vegetation compared with improved pasture, and a management comparison, reduced-input cropping compared with conventional cropping. Data were analysed using three different meta-analytical techniques, including a simple vote counting method and a formal fixed-effects/random-effects meta-analysis. Results, Arthropod richness was significantly higher in areas of less intensive land use. The decline in arthropod richness was greater between native vegetation and agricultural land uses than among different agricultural land uses. These patterns were evident for all taxa combined, predators and decomposers, but not herbivorous taxa. Overall, arthropod abundance was greater in native vegetation than in agricultural lands and under reduced-input cropping compared with conventional cropping. Again, this trend was largely mirrored by predators and decomposers, but not herbivores. Main conclusions, The greater arthropod richness found in native vegetation relative to agricultural land types indicates that in production landscapes still containing considerable native vegetation, retention of that vegetation may well be the most effective method of conserving arthropod biodiversity. Conversely, in highly intensified agricultural landscapes with little remaining native vegetation, the employment of reduced-input crop management and the provision of relatively low-intensity agricultural land uses, such as pasture, may prove effective in maintaining arthropod diversity, and potentially in promoting functionally important groups such as predators and decomposers. [source]

Modelling stream flow for use in ecological studies in a large, arid zone river, central Australia

Justin F. Costelloe
Abstract Australian arid zone ephemeral rivers are typically unregulated and maintain a high level of biodiversity and ecological health. Understanding the ecosystem functions of these rivers requires an understanding of their hydrology. These rivers are typified by highly variable hydrological regimes and a paucity, often a complete absence, of hydrological data to describe these flow regimes. A daily time-step, grid-based, conceptual rainfall,runoff model was developed for the previously uninstrumented Neales River in the arid zone of northern South Australia. Hourly, logged stage data provided a record of stream-flow events in the river system. In conjunction with opportunistic gaugings of stream-flow events, these data were used in the calibration of the model. The poorly constrained spatial variability of rainfall distribution and catchment characteristics (e.g. storage depths) limited the accuracy of the model in replicating the absolute magnitudes and volumes of stream-flow events. In particular, small but ecologically important flow events were poorly modelled. Model performance was improved by the application of catchment-wide processes replicating quick runoff from high intensity rainfall and improving the area inundated versus discharge relationship in the channel sections of the model. Representing areas of high and low soil moisture storage depths in the hillslope areas of the catchment also improved the model performance. The need for some explicit representation of the spatial variability of catchment characteristics (e.g. channel/floodplain, low storage hillslope and high storage hillslope) to effectively model the range of stream-flow events makes the development of relatively complex rainfall,runoff models necessary for multisite ecological studies in large, ungauged arid zone catchments. Grid-based conceptual models provide a good balance between providing the capacity to easily define land types with differing rainfall,runoff responses, flexibility in defining data output points and a parsimonious water-balance,routing model. Copyright 2004 John Wiley & Sons, Ltd. [source]

Managing forests, livestock, and crops under global warming: a micro-econometric analysis of land use changes in Africa,

S. Niggol Seo
This paper examines potential land use changes in Africa under climate change by building an integrated model of crop management, animal husbandry, and forestry. Using micro-level decisions from around 9000 household surveys in 11 countries, we analyze the choice of land types across the landscape with a multinomial discrete choice model. The choices and future adaptation measures are analyzed as a mosaic based on the typology of Agro-Ecological Zones. The results indicate that if climate becomes hotter and drier, Africa will adapt by increasing a joint production of crops and animals, especially in the lowland savannahs. On the other hand, if climate becomes wetter, it will switch more to forests, either with crops or with both crops and livestock, especially in the mid and high elevation humid zones. Forestry will play a significant role in adaptation when a substantial increase in precipitation makes animal husbandry an unattractive alternative. [source]